Endodontics Flashcards
what is clinical assessment of a RCT tooth?
Coronal seal - restorations/crowns. Leakage? Caries?
Amount of remaining tooth structure- ferrule
Is the tooth restorable? Can you isolate it with rubber dam?
Swelling
Sinus
TTP
Buccal sulcus - tender to palpation?
Mobility
Increased pocketing – periodontal disease and root fractures
what is radiographic assessment of a RCT tooth?
Root filling - length, quality of obturation e.g. voids
Unfilled/missed root canals
Shape of canal
Patency - fracture instruments, posts, sclerosis
Bone support – mild, moderate, severe
Crown to root ratio (1:1.5)
Pathology - periapical radiolucency – healing?, resorption, perforations
what must be done with inadequate root fillings?
be re-treated before restoration
what are problems after RCT/re-RCT?
Amount of remaining tooth structure - externally and internally
Restoration type
Lack or no ferrule
Wide post holes e.g. re-RCT
Endodontic complications - fractured instruments, perforations, short/long root fillings
how long can root filled teeth be unrestored?
Root filled teeth unrestored for 3 months or longer should generally be re-root canal treated
what is the importance of coronal seal?
Technical quality of the coronal restoration significantly more important for apical periodontal health than the technical quality of the root canal treatment
what are anterior restoration options?
Anterior teeth with intact marginal ridges
Composite restoration
(Veneer)
what are anterior restoration options?
Anterior teeth with intact marginal ridges + discoloured crown
Bleaching or
Veneer
(Crown)
what are anterior restoration options?
Anterior teeth with marginal ridges destroyed (post core crowns)
Core build –up with crown
Post crown
what is a post/core?
Gains intraradicular support for a definitive restoration
Core provides retention for crown
Post retains the core
Posts do not strengthen or reinforce teeth
Preparation of the root canal for a post, weakens the tooth
what is components of a post and core?
Post - placed in the root canal
Core - is what the prosthesis is cemented to e.g. crown or bridge abutment
what are guidelines for post placement?
- tooth type
- root filling length
- post width
- Sufficient alveolar bone support, at least half of post length into the root
- Minimum 1:1 post length/crown length ratio
- ferrule
what is tooth type guidelines for post placement?
Incisors and canines - post unnecessary if sufficient coronal dentine is present
Avoid in mandibular incisors due to thin/tapering/ narrow mesiodistal roots
Premolars - small pulp chambers and tapering roots. Thin in mesiodistal cross-section and proximal invaginations. If a post is to be placed then place in the widest root canal. Avoid in curved canals to avoid perforations!
in terms of placing posts when must you avoid doing them?
Avoid in curved canals to avoid perforations
what is root filling length guidelines for post placement?
4-5mm root filling apically
what is post width guidelines for post placement?
No more than 1/3 of root width at narrowest point and 1 mm of remaining circumferential coronal dentine
what is ferrule guidelines for post placement?
At least 1.5mm height and width of remaining coronal dentine
what is a ferrule? what does it prevent? what may be necessary to achieve this?
Dentine collar. Encirclement of 1- 2 mm of vertical axial tooth structure within walls of a crown
Prevents tooth fracture
If crown margin is not placed onto solid tooth, root fracture significantly increased
Orthodontic extrusion or crown lengthening may be necessary to achieve this
what is the ideal post?
- Parallel sided
- Non-threaded (Passive)
- Cement Retained
what does parallel sided refer to in terms of ideal post?
Avoids ‘wedging’
More retentive than tapered
what does non-threaded(passive) refer to in terms of ideal post?
Smooth surface incorporates less stress to remaining tooth than threaded (Active)
what does cement retained refer to in terms of ideal post?
Less retentive than threaded posts but cement acts as buffer between masticatory forces and post/toot
what are the classification of posts?
Manufacture – pre-formed/prefabricated or custom made
Material – cast metal, steel, zirconia, carbon/glass fibre
Shape – parallel sided or tapered
what are prefabricated posts?
Only 1 visit required
No impressions and laboratory visit required
Chairside core build-up
Post and core are different materials
Immediate preparation of core
Large selection of designs and materials
what are custom posts? how many visits required? and how made?
Cast from direct pattern fabricated in patients mouth e.g. Duralay
Indirect pattern can be fabricated in the lab e.g. impression of the post hole and wax-up of post and core in lab (most common method)
Unified post and core e.g. made one piece, the same material
2 visits required – impressions and fit. Temporisation between visits and lab stage required. Risk of contamination of the root canal between visits.
Cast post made in Type IV heat hardened gol
what types of post material? and their properties?
Metal - cast gold, stainless steel, brass, titanium
Poor aesthetics, root fracture, corrosion, nickel sensitivity. Radiopaque on radiographs.
Ceramics - alumina, zirconia
High flexural strength and fracture toughness. Favourable aesthetics. Difficult retrievability and root fracture common
Fibre - glass, quartz, carbon
Flexible, similar properties to dentine. Aesthetic, retrievable, bond to dentine with DBA’s. Radiolucent on radiographs.
what is a core-build up?
Internal part of tooth is built-up with restorative material to replace the lost tooth tissue
The core is prepared. It provides retention and resistance for definitive restorations
what are core materials? and their properties?
Composite – most commonly used core material. Tooth coloured so good aesthetics. Bonds to the tooth structure. Technique sensitive, so moisture control required. Used with fibre posts
Amalgam - tend to avoid as retention is required. Poor aesthetics. Core cannot be prepared straightaway – need 24hrs to set. Avoid pinned amalgams.
Glass ionomer - not really used as it absorbs water and core expands in size
what is nayyar core?
Root treatment is removed from the root canals.
Amalgam is packed into the root canals and tooth built-up. This provides retention for the amalgam
Cannot be prepared for 24 hrs until amalgam sets
what is core design? degree of taper and length required?
Core – taper and length important
6 degree taper
Length required - to allow 2 mm clearance for MCC
how to remove gutta percha and what is essential?
Dental dam (pros and cons)
Soften (heat / solvent)
Gates gliddens to minimum size 3 (straight part of canal only)
Use working length and rubber stopper on gates Glidden
Essential to leave 3 – 5 mm GP in apical third
what are problems with posts?
Perforation
Core fracture
Root fracture or crack
Post fracture
how to manage post perforation?
Repair – internal or external (periradicular surgery)
Extraction
what is used to remove posts?
Ultra-sonics
Masseran Kit
Eggler
Moskito Forceps (screw retained)
what are post failure rates?
60% due to Restorative reasons
32% due to Periodontal problems
8% due to Endodontic reasons
